Re: [Haskell] [Haskell-cafe] ANN: psqueue-benchmarks - benchmarks of priority queue implementations
Hey Scott, I quickly tried your suggestion, plugging in foldr' from Data.Foldable and sprinkling a few seqs in some places, but it doesn't help the stack overflow. On Fri 29 Mar 2013 16:23:55 GMT, Scott Dillard wrote:
I do not know why it overflows. It's been a while, but isn't the answer usually "too much laziness"? Maybe try changing the foldr in fromList to foldr'? I would try it out quickly but do not have ghc installed on any computers here.
I am happy start a repo for this library, but there is not much history to import so anyone else may do it. I'm not sure how hackage upload permissions work... I guess I just change the maintainer field in the .cabal file from myself to someone else...? Any volunteers?
On Thu, Mar 28, 2013 at 11:16 PM, Kazu Yamamoto <kazu@iij.ad.jp <mailto:kazu@iij.ad.jp>> wrote:
Hi Niklas,
> * PSQueue throws a stack space overflow if you try to put in 100000 > * Ints
A slightly different implementation is used in GHC:
https://github.com/ghc/packages-base/blob/master/GHC/Event/PSQ.hs
Could you test it? If this code also has the same problem, I need to fix it.
--Kazu
I had a 5 second look at the PSQueue implementation and here's what I got so far: * fromList should use foldl'. * LTree should be spine strict (i.e. strict in the (LTree k p) fields). * Winner should be strict in the (LTree k p) field and probably in all other fields as well. This is a nice example showing that strict fields is the right default. If fields need to be lazy there should ideally be a comment explaining why that is needed (e.g. in the case of finger trees and lists). On Fri, Mar 29, 2013 at 9:53 AM, Niklas Hambüchen <mail@nh2.me> wrote:
Hey Scott,
I quickly tried your suggestion, plugging in foldr' from Data.Foldable and sprinkling a few seqs in some places, but it doesn't help the stack overflow.
On Fri 29 Mar 2013 16:23:55 GMT, Scott Dillard wrote:
I do not know why it overflows. It's been a while, but isn't the answer usually "too much laziness"? Maybe try changing the foldr in fromList to foldr'? I would try it out quickly but do not have ghc installed on any computers here.
I am happy start a repo for this library, but there is not much history to import so anyone else may do it. I'm not sure how hackage upload permissions work... I guess I just change the maintainer field in the .cabal file from myself to someone else...? Any volunteers?
On Thu, Mar 28, 2013 at 11:16 PM, Kazu Yamamoto <kazu@iij.ad.jp <mailto:kazu@iij.ad.jp>> wrote:
Hi Niklas,
> * PSQueue throws a stack space overflow if you try to put in 100000 > * Ints
A slightly different implementation is used in GHC:
https://github.com/ghc/packages-base/blob/master/GHC/Event/PSQ.hs
Could you test it? If this code also has the same problem, I need to fix it.
--Kazu
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Niklas Hambüchen